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Z OLD Tissues of the Body > Immunity > Flashcards

Flashcards in Immunity Deck (191):
1

Do most microorganisms cause disease in humans?

Most don’t, but some do

2

What are pathogens?

Disease causing microorganisms

3

What do pathogens include?

- Protozoa
- Bacteria
- Viruses 
- Fungi 
- Worms

4

What are both humans and pathogens made from?

Proteins, carbohydrates and lipids

5

What are the roles of protein in pathogens?

- Nutrient acquisition 
- Reproduction 
- Locomotion 
- Respiration

6

How do humans and pathogens differ in their proteins?

They posses radically different proteins, that allow them to survive in their respective niches

7

What do different proteins have?

Different amino acid sequences

8

What is the significance in the difference in amino acid sequences?

The immune system detects this difference

9

What is damage to the host an inevitable consequence of?

Breaking through barriers in order to gain access to regions that are most prosperous

10

What is an inevitable consequence of damage to the barriers?

Alert

11

What is the first barrier to infection?

Epithelia

12

What does epithelia do to prevent infection?

Keep body clear of pathogens

13

How do we facilitate the clearance of pathogens from epithelial surfaces?

- Rapid epithelial regeneration 
- Blinking
- Flow of tears
- Ear wax
- Nasal hairs
- Coughing
- Sneezing
- Mucociliary escalator
- Vomiting
- Digestive enzymes
- Peristaltic gut movement
- Regular urine flow

14

How quickly do epithelial cells function on contact with a pathogen?

Within seconds

15

Essentially, what is epithelium?

A mechanical, selectively permeable barrier between the ‘outside’ and the ‘inside’

16

What may epithelial cells posses?

Motile cilia

17

Can epithelial cells renew?

Yes, rapidly

18

What is the purpose of motile cilia on epithelial cells?

Keep surface free of bacteria

19

What do epithelial cells produce?

- Natural antibodies 
- Cytokines
- Chemokines 
- May produce mucins

20

What kind of natural antibodies do epithelial cells produce?

Cationic antibacterial peptides

21

Give 2 examples of cationic antibacterial peptides?

- Defensins 
- Cathelicidins

22

What are cytokines?

Proteins that alter the behaviour of other cells

23

What are chemokines?

Proteins that attract other cells by gradients

24

Where to epithelial cells transport antibodies to and from?

From inside to outside

25

What is the primary role of epithelial cells?

To block the entry of microorganisms

26

What must be done for pathogens with non-self proteins to break through the epithelial barrier?

They must damage it

27

What happens to epithelial cells on contact with microorganisms?

They are activated

28

What do activated epithelial cells produce?

Chemokines and cytokines

29

What is the result in the production of chemokines and cytokines?

A much more permeabilised epithelium

30

What is the result of a more permeabilised epithelium?

#NAME?

31

What is the result of opsonisation of foreign materials?

Pathogens more readily phagocytosed

32

What happens after a pathogen is phagocytosed?

It raises a specific response

33

What is the result of the specific response to a phagocytosed pathogen?

Interaction with other cells of the innate and adaptive immune system

34

What promotes vascular permeability?

Many inflammatory mediators- immunoglobulin and complement

35

What is the result of vascular permeability?

Mediators are leaked into the inflamed site through the endothelial cells lining blood vessels

36

What do inflammatory mediators do?

- Increase permeability 
- Increase migration of macrophages, neutrophils and lymphocytes into tissue 
- Increases SA to volume ratio

37

What does increased permeability allow?

Increased fluid leakage from blood vessels and extravasation of antibodies and complement at site of infection

38

What is the result of increased migration of macrophages, neutrophils and lymphocytes?

Increases microbicidal activity

39

What is the result of an increased SA to volume ratio?

Better gas exchange

40

What is the result of action of inflammatory mediators?

Allows for immunofunction to be increased

41

What is inflammation a response to?

Infection

42

What does inflammation lead to?

- Heat
- Swelling 
- Redness
- Pain 
- Loss of function

43

What is the purpose of inflammation?

Protects area from further damage

44

What is the innate immune response?

Inbuilt immunity to resist infection

45

When is innate immunity present from?

Birth

46

Is innate immunity specific?

No

47

Is innate immunity enhanced by secondary exposure?

No

48

What kind of components does innate immunity use?

Cellular and humoral

49

Is innate immunity effective alone?

No, poorly effective without adaptive immunity

50

What is innate immunity involved in?

Triggering and amplification of adaptive immune response

51

What is adaptive immunity?

Immunity established to adapt to infection

52

How is adaptive immunity obtained?

Learnt by experience

53

What does adaptive immunity confer?

Pathogen-specific immunity

54

Is adaptive immunity enhanced by second exposure?

Yes

55

Does adaptive immunity have memory?

Yes

56

What kind of components does adaptive immunity use?

Cellular and humoral

57

Is adaptive immunity effective without innate immunity?

No

58

What do antibodies reflect?

Infections to which an individual has been exposed to already

59

What are antibodies diagnostic for?

Infection

60

How has the adaptive immune system evolved?

#NAME?

61

What is the importance of innate immunity implied by?

- Rarity of inherited deficiencies in innate immune mechanisms 
- Considerable impairment of protection when deficiencies in innate immunity occurs

62

What cells are involved in innate immunity?

- Macrophages and monocytes
- Neutrophils 
- Basophils 
- Eosinphils 
- Natural killer cells

63

What are the roles of macrophages and monocytes?

- Phagocytosis 
- Presentation to lymphocytes

64

What are the roles of neutrophils?

- Phagocytic 
- Anti-bacterial

65

What is special about polymorphonucleur neutrophils?

They have 5 lobes to their nuclei

66

What are the roles of mast cells and basophils?

#NAME?

67

What are the roles of eosinphils?

- Anti-parasite 
- Causes allergies

68

Describe the nucleus of lymphocytes?

It almost fills the cytoplasm

69

What kind of cells are phagocytes?

#NAME?

70

What is meant by a phagocyte?

A cell able to engulf and destroy bacteria, extracellular viruses and immune complexes

71

What is phagocytosis?

Active engulfment of particles into a phagosome

72

What is formed form a phagosome and a lysosome?

Phagolysosome

73

What occurs in a phagolysosome?

Digestion

74

What happens to neutrophils in healthy tissues?

They are normally excluded

75

Why are bites taken so seriously?

Because the mouth is the most contaminated site in the body, and the microbes in the mouth can enter the wound when bitted

76

What are neutrophils specialised for?

Working under anaerobic conditions

77

Why are neutrophils adapted for working anaerobic conditions?

Because these prevail in damaged tissues

78

When does neutrophil arrival occur in an inflammatory response?

First event

79

What happens once a neutrophil has been activated?

They become unable to synthesise new granules

80

What happens once all granules have been used up?

The neutrophil dies

81

What do patients with neutrophil deficiencies suffer from?

Recurrent infection, often by microbes of the normal commensal flora

82

Why do patients with neutrophil deficiencies often suffer from recurrent infections?

Because they have limited phagocytic action

83

What can phagocytes sometimes to?

Release their lysosome contents on the outside of pathogens

84

Why would phagocytes release their lysosomal contents onto the surface of pathogens?

If they were too big to digest

85

What binds to neutrophil receptors?

Bacteria

86

What does bacterial binding to neutrophil receptors induce?

Phagocytosis and microbal killing

87

What do neutrophils have for phagocytosis?

Elaborate receptors

88

What do neutrophils do to the bacteria bound to them?

Engulf and digest

89

What do CD14 and CR4 bind to?

Bacterial lipopolysaccharide (LPS)

90

What do macrophages do?

Phagocytose microbal, or damaged and unwanted cells

91

What do macrophages release?

A variety of cytokines

92

What are the cytokines released by macrophages important for?

Innate and adaptive immunity

93

Do macrophages live long?

Yes

94

Why are macrophages long-lived?

Because they continue to generate more lysosomes as needed

95

What do macrophages act as?

Professional antigen presenting cells (APCs)

96

Where are APCs important?

In the development of adaptive immunity

97

What do APCs do?

Show antigens to T lymphocytes for their action

98

What is opsonisation?

The coating of an microorganism by antibodies or complement to render in recognisable as foreign by phagocytes

99

What does opsonisation enhance?

Phagocytosis

100

When are encapsulated bacteria more efficiently phagocytosed?

When coated with antibody and C36

101

What can encapsulated bacteria not be engulfed by?

Neutrophils

102

What does antibody bound to bacteria activate?

Complement binding of C3b to bacteria

103

What is engulfment of bacteria by neutrophils mediated by?

Fc receptors and complement receptors

104

What do granules fuse with?

Phagosomes

105

What happens when granules fuse with phagosomes?

Toxic oxygen metabolites that kill bacteria released

106

What are natural killer (NK) cells a part of?

Innate immune system

107

Are NK cells T or B cells?

Neither

108

Do NK cells have classical antigen receptors?

No

109

What do NK cells do?

Recognise and kill abnormal cells

110

Give an example of an abnormal cell NK cells can kill?

Tumour cells

111

What is the result of NK cells killing tumour cells?

Stops cancer developing

112

What do NK cells do in virus-infected cells?

Directly induce apoptosis

113

How do NK cells induce apoptosis in virus-infected cells?

By pumping proteases through pores that they make in target cells

114

What are NK cells similar to?

Cytotoxic T cells

115

How do NK cells differ from cytotoxic T cells?

They have no specific T cell receptors

116

What do NK cells provide?

Innate immunity against intracellular infections

117

What happens in people lacking NK cells?

They suffer from persistent viral infections, particularly herpes virus

118

What leads to NK cell activation in most cells?

IFNα and IFNß

119

What leads to NK cell activation in macrophages?

IL-12 and TNFα

120

What do NK cells provide regarding a virus infection?

An early response

121

What do viral infections induce?

Cells to secrete a burst of cytokines

122

What do cytokines induce?

The proliferation and activation of NK cells

123

What happens while NK cells act?

A slower cytotoxic T cell response develop which helps to clear the infection

124

What are the secretory molecules of the innate response also known as?

Humoral components

125

What are the humoral components on the innate immune respose?

- Transferrin and lactoferrin 
- Interferon 
- Lysozyme 
- Fibronectin 
- Complement components and their products 
- TNF-α

126

What does transferrin and lactoferrin do?

Deprives microorganisms of iron

127

What does interferon do?

Inhibits vital replication and activates other cells which kill pathogens

128

Where are lysozymes found?

In serum and tears

129

What do lysozymes do?

They break down the bacterial cell wall of some gram+ bacteria

130

What are lysozymes in synergism with?

Antimicrobal peptides

131

What does fibronectin do?

Opsonises bacteria, and promotes their rapid phagocytosis

132

What do complement proteins and their products cause?

Destruction of microorganism, directly or with help of phagocytic cells

133

What does TNF-α do?

Suppresses viral replication and activates phagocytes

134

Why is the complement system so named?

Because is was discovered as heat-labile components which complemented or enhanced the oponising effects of antibody

135

What does the complement system do?

Marks pathogens for destruction

136

How does the complement system mark pathogens for destruction?

By covalently binding to their surface

137

Evolutionarily, what came first, the complement system or the antibody response?

The complement system

138

What did the antibody response evolve to do?

Enhance the mechanism of complement activation and phagocytosis

139

Where are complement proteins found?

Ubiquitous in the blood and lymph

140

How long after an infection begins can the complement system be used?

Immediately

141

What does an antibody do to the complement system?

Enhances complement activation

142

What are the complement components?

C1-C9

143

How do different complement proteins differ from each other?

They have different functions

144

What are C5a, C3a and C4a responsible for?

Recruitment of inflammatory response

145

What is recruitment of inflammatory cells important for?

Recruitment for host defence against infection

146

What is C3b responsible for?

Opsonisation

147

What is responsible for the direct killing of pathogens?

MAC (membrane attack complex) using C5-C9

148

What does the MAC do?

Assembles to make a pore in the pathogen membrane

149

What does the MAC assemble?

- C5b binds to C6 and C7
- C5b, 6 and 7 complexes bind to membrane via C7
- C8 binds to the complex, and inserts itself into the membrane
- C9 molecules bind to the complex and polymerise
- 10-16 molecules of C9 bind to form a pore in the membrane

150

What happens if there is a deficiency in C1, 2 or 4?

Immune complex disease (type III)

151

What happens if there is a deficiency in C3?

Recurrent bacterial infection

152

What happens if there is a deficiency in C5-9

Recurrent Neisserial infection

153

What do T and B lymphocytes respond to?

Antigens

154

What are antigens?

Molecules that elicit a specific immune response when introduced to the tissues of an animal

155

What does the common lymphocyte precursor (CLP) give rise to?

T cells and B cells

156

Where do T cells develop?

Thymus

157

Where do B cells develop?

Bone marrow

158

What to T cells give rise to?

T helper cells (Th) and cytotoxic T lymphocytes (CTL)

159

What do Th cells do?

Activate B cells and macrophages

160

What do CTLs do?

Kill virus infected cells

161

What do B cells give rise to?

Plasma cells

162

What do plasma cells do?

Produce antibodies

163

What happens when B cells are activated?

They get much bigger with lots of RER

164

What is true of T and B cells until they encounter an antigen?

They are essentially inactive

165

What do T and B cells express?

Antigen receptors

166

What is the B cell receptor?

A membrane bound antibody surface immunoglobulin

167

What is the T cell receptor?

A distinct molecule called a T cell antigen receptor

168

What does each antigen receptor bind to?

A different antigen

169

How many antigen specificity does each cell have?

1

170

What does the T cell receptor resemble?

A membrane bound Fab fragment

171

What are 3 main ways antibodies protect the host from infection?

- Neutralisation 
- Opsonisation 
- Complement activation

172

What happens in antibody neutralisation?

Prevents bacterial adherence, stopping it binding to the cell

173

What does each lymphocyte express?

A single antigen receptor specificity

174

How many lymphocytes are there in the body?

Millions

175

What does each naive lymphocyte bearing a unique receptor represent?

A potential progenitor of a genetically identical clone of daughter cells

176

What does the clonal distribution of antigen receptors mean?

That lymphocytes of a particular specificity will be too infrequent to mount an effective response

177

What is the purpose of clonal selection?

It raises the clonal frequency of cells with a particular antigen specificity

178

What does antigen interaction lead to?

Lymphocyte activation

179

What do daughter cells of activated lymphocytes bear?

Identical antigen specificity to the parent cell

180

What does a B lymphocyte do on activation?

Attaches to foreign material

181

What does the attachment of B lymphocytes to foreign material cause?

Clonal expansion

182

What does clonal selection induce?

Proliferation and increase in effector frequency

183

What are the phases of the adaptive immune response?

- Recognition phase
- Activation phase
- Effector phase
- Decline homeostasis 
- Memory

184

What happens during the recognition phase?

Clonal selection

185

What happens during the activation phase?

Clonal expansion

186

What happens during the effector phase?

Differentiation to effector cells

187

What does the clonal nature of the adaptive immune response allow for?

Immune logical memory

188

What must happen for T helper cells to be able to ‘see’ something foreign?

Presentation to them by antigen presenting cell

189

What must happen for B cells to become plasma cells?

Must be given permission by T helper cells

190

What does almost every cell type bear?

MHC class 1

191

What is the result of almost every cell type possessing MHC class 1?

Can present endogenous antigen to cytotoxic T cells